Magnetically-induced synthesis of highly-crystalline ternary chalcopyrite nanocrystals under ambient conditions

We report a novel and facile method to synthesize phase pure, chemically homogeneous, and highly crystalline CuInS₂, an important element for optoelectronics, optics, and solar energy applications. This ternary semiconductor compound is grown by magnetic Zn doping under high-frequency magnetic induction at ambient conditions. The magnetic doping gives superparamagnetic heating of the resulting nanocrystals via magnetic induction, causing an accelerating growth rate of the doped CuInS₂ under ambient conditions of 2-3 orders of magnitude faster than conventional autoclave synthesis. Shape evolution of the Zn doped CuInS₂ nanocrystals from initially spherical, to pyramidal, cubic, and finally to a bar geometry, was detected as a function of time of exposure to magnetic induction. These newly-synthesized nanocrystals demonstrated considerably improved optical emission properties compared to those prepared via conventional autoclave methods. Nanostructural development of the nanocrystals was well characterized and a mechanism of crystal growth was proposed.